There is a single inlet for both city and tank with a valve that allows you to switch between the two. When it's in Tank Fill position no water flows in. There is a little pump button but that seems to turn on briefly then off.

The low point drains is for draining your water lines for the winter. A least that what mine are for. If you are switch to tank fill, water should be flowing in the tank, unless you have a kick hose behind the panel or somewhere....or it's plugged up with something. In order to get water to r fixtures from the tank u have to turn on the water pump.

Can u hook up an air valve and try blowing the line out. Do not put more than 40 psi in the line. Be sure r vent to the tank is not plugged up, otherwise the pressure may rupture the tank.

It's a new unit so I have never used it before. The dealer said they went through the de-winterizing process and made sure everything worked. Either they didn't or I just don't know what I'm doing. Either is very possible.